Amyotrophic Lateral Sclerosis (ALS) - Questions and Answers Print E-mail

What is ALS?
Answer: ALS is a progressive disease of the motor neurons.

Question: What are the motor neurons?
Answer: The motor neurons are the nerve cells that are located in the brain, brain stem and the spinal cord, and represent the central station of the motor nerves that supplies the voluntary muscles throughout the body.

Question: What are the symptoms and signs of ALS?
Answer: ALS patients usually present with a progressive weakness of different groups of voluntary muscles. The most commonly effected muscles are those of the tongue and swallowing, leading to the slurring of speech and difficulty in swallowing. The upper and lower extremity muscles are also affected, leading to wasting and twitching of these muscles. The involvement of the upper motor neurons that are located in the cerebral cortex causes an increase in the reflexes and tone of the effected muscles. This mixture of the involvement of the upper and lower motor neurons is the hallmark of the diagnosis of ALS.

Question: What functions are usually not affected by ALS?
Answer: Involuntary muscles, such as those that move the bowel and stomach, are usually not affected. The muscles that move the eyes are not affected. Urinary incontinence and bowel incontinence is very uncommon due to the lack of involvement of the involuntary muscles of the bladder and bowel. Sexual function is preserved. Sensation is not affected. Vision, hearing and mental status remains intact usually throughout the course of the disease.

Question: What is the target age group of ALS?
Answer: ALS affects all age groups and both sexes, but the disease usually strikes adults between 35 and 65 years old.

Question: How is ALS diagnosed?
Answer: Clinical evaluation is essential. The involvement of the upper and lower motor neurons is the diagnostic hallmark of the disease. Upper motor neuron involvement is expressed as increased reflexes. Lower motor neurons involvement presents as a weakness and wasting of the bulbar and the limb muscles. The presence of increased reflexes in wasted muscles is very typical.

EMG is the most important diagnostic test. It involves inserting electrodes into the involved muscles and measuring the electrical activity.

Muscle biopsy, in which a piece of muscle is removed under local anesthesia, may help to establish the diagnosis, although the findings are not pathognomonic.

Question: What does a muscle biopsy show in ALS?
Answer: ALS is not diagnosed by muscle biopsy. Muscle biopsy may be needed to look for evidence of loss of nerve supply (denervation) to muscles that are not clinically involved. Denervation, in a clinically strong muscle proves the notion of widespread denervation, which is the diagnostic hallmark of the disease. Denervation in the muscle biopsy is identified by NADH reaction. Denervated fibers look like small and angular, and stain excessively with NADH. In less progressive forms of ALS, reinnervation is also demonstrated in ATP-ase reaction. Muscle biopsy also helps to exclude certain myopathies, which can mimic ALS, such as inclusion body myositis and acid maltase deficiency.

Question: What is the prognosis of ALS?
Answer: ALS progresses within 3-5 years. Usually, death results from paralysis of the respiratory muscles or aspiration pneumonia. The disease is more progressive if it starts in the bulbar muscles, leading to difficulty in swallowing and speech, followed by difficulty in breathing. Some cases progress very slowly over decades.

Question: Is ALS hereditary?
Answer: About 10% of ALS patients have a family history of the disorder. Recently, a mutation in the SOD1 gene on chromosome 21 has been identified as a cause of this type of ALS.

Question: Is ALS treatable?
Answer: So far, no cure has been found for ALS. Riluzole, a glutamate antagonist, is the first medication ever approved for treatment of ALS. It seems to modestly extend survival time. Other medications are being tested, such as Gabapentin. Neurotrophic growth factors are also being tried.

Question: Why is ALS also referred to as Lou Gehrig's disease?
Answer: ALS first came to the wide public attention when the Hall of Fame career of Yankee's first baseman, Lou Gehrig, was cut short by the disease in 1939. Gehrig died in 1941. Many people still use the term, Lou Gehrig's disease, when referring to ALS.
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